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Indian River Field Laboratory Mimeo Report 64-3 -- April 1, 1964

A PROGRESS REPORT ON POTENTIAL SUMMIER-GROWING PERENNIAL LEGUES
FOR SOUTH FLORIDA I...

Albert E. Kretschmer, Jr.1/ '

Kretschmer in 1962 (1) and 1963 (2) reported preliminary invest
summer-growing perennial legumes. Most of the planting material came.
U.S.D.A. Regional Plant Introduction Center in Experiment, Georgia, the U.S.D.A.
Plant Materials Center, Arcadia, Florida or from Australia (1). Almost all are
native to countries having subtropical or tropical climates. Their potential
adaptation to Florida conditions depends primarily on frost tolerance. From
this standpoint, the further south the better chance for survival (3). Other
important contributing factors may be their ability to compete with Florida's
pasture grasses, water table fluctuations, soil fertility, etc.

The object of this report is to summarize information obtained during the
past year of the more prominent species that have been in the observational
and replicated tests. The companion grass was pangolagrass except in a few
instances when the legume was grown alone.

LOTiOONIS BAINESII

This prostrate perennial legume appears to reach its maximum growth rate
in the spring although there is a second rapid growth period in the early fall.
It has been difficult to establish the ability of Lotononis to grow in the summer
because of a combination of grass competition and its susceptibility to at least
two soil-borne diseases, Rhizoctonia and Sclerotium rolfsii. Less damage from
these diseases, which initially affected plant growth in late May 1963, appears
to result from frequent clipping and, or, growing in combination with pangolagrass.
The disease incidence appears to remain high through the summer until September
or October. Older plants (produced from seeds that germinate in the fall and
winter) appeared to be more disease susceptible than those from seeds germinating
in the spring. The rapid growth rate of Lotononis runners may permit summer
live-over, in spite of the diseases, especially when the runners grow into areas
unoccupied by the legume. Those plants that "live over" the summer or those from
seeds that germinate in August or September and survive grow rapidly until about
November when growth rates are reduced.

Lotononis is more frost resistant than pangolagrass but winter growth is
slow and would not contribute much dry matter to the feed program.

The rapidity of spring growth is emphasized by the number of inches of
stolon (runner) elongation. Stolon growth of four individual plants were ob-
served from March 13 to April 19, 1963. They had 13 to 35 individual stolons
per plant. Elongation of from 4 to 13 stolons per plant was measured on a weekly
basis. For the period of 37 days the average growth (elongation) rate per stolon
was about 0.7 inches per day; and the total daily growth of all stolons per plant
was 15.7 inches per day (average inches per stolon per day times total number of
stolons per plant).

l/ Associate Agronomist, University of Florida, Indian River Field Laboratory,
Ft. Pierce, Florida.

-2-

Protein analyses of Lotononis are limited but one analysis of roots showed
11.1 percent and the above-ground portion contained 21.2 percent crude protein.
In June and July of 1963 mixtures of Lotononis and pangolagrass contained 13 to
14 percent crude protein. It was obvious that nitrogen from Lotononis roots is
released in considerable quantities and is utilizable by the grass.

Although little is known of the lime requirements of Lotononis in one green-
house test 2 tons of hi-calcic lime plus 100 pounds each of potash (K 0) and
phosphate (P20 ) per acre produced the most vigorous plants. Next best production
was with half of the above rates. Treatments of less than 2000 pounds of lime
or 50 pounds of K20 and P205 at seeding produced much less vigorous plant growth.

SIRATRO

(Phaseolus atropurpureus)--The original planting of this heavy seed-producing
legume in Florida was made at the Indian River Field Laboratory on June 20, 1962.
Seedlings were transplanted from the greenhouse to a ten foot row. The original
plants are still living and seed production from these has resulted in the germina-
tion and survival of many new plants. Also, seedlings were transplanted to a
fence-row on March 18, 1963 for seed collection purposes. Also, replicated plots
with Siratro-pangolagrass combinations are being compared with other summer-
growing legumes.

This has been rated the summer-growing perennial legume with the best potential
in south Florida. It has an extremely large taproot that should enable it to
survive on well-drained soils. Also, it can withstand high water tables for short
periods of time as evidenced by growth on flatwoods soils. Preliminary tests
indicate that although it's optimum lime, potash and phosphate requirements may
be similar to those for Lotononis bainesii, smaller lime or fertilize applications
will not result in the large growth decreases that occur with Lotononis.

Crude protein analysis have been made on several samples. Different sections
of mature stolons (about the diameter of a pencil and a year old) had crude
protein contents of from 8 to 12%. Fractionation of one plant shoot (about
18 inches long) showed the percent crude protein to be concentrated in the
following manner: leaves plus stems--19.3, seed stalks--15.3, immature seed
pods plus seeds--25.2, almost mature seed pods (still green color)--15.2, almost
mature seeds--21.1, mature seed pods (brown)--7.8, mature seeds--32.4. When
growing in combination with pangolagrass, protein contents of the mixture were
found to vary from 7.9 to 11.1 percent depending upon the quantity of Siratro
present.

It is not known how far north Siratro can grow as a perennial. However,
seeds or plants have been distributed to experiment stations in north and west
Florida and a good stand was established last summer at Gainesville. Because
new shoots from Siratro evidently can arise from any portion near the crown of
the plant either above or below the soil surface, a well-developed taproot
and plant, although frozen back to the soil, may be able to generate new shoots
in the spring. The number of these freezes and the interval between them would
be an important factor to consider. At present it is believed that Siratro will
grow as a perennial in Zones E, F, G, II, I, J, and K as outlined by the Federal-
State Frost Warning Service. This includes that part of Florida south of a line
from about Titusville to Brooksville.

An effort is being made to collect sufficient seeds this summer so that small
commercial quantities will be available next spring.

-3-

STYLOSANTHES IHUMILIS (0)

This summer-growing annual, sometimes is called Townesville Lucerne (alfalfa)
or Stylo by Australians. They have used it in rather extensive areas. It is a
moderate forage producer, and an abundant hard seed producer, making self regenera-
tion a reality. A 10 foot row was seeded in June 1961 and a stand was not obtained.
On November 9, a second 10 foot row was seeded. On June 20, 1962, plants were
beginning to form a mat, began to flower in late July and were growing rapidly.
Seeds began to mature in early November 1962. A good stand was obtained in the
same area in the summer 1963.

On February 15, 1963, four plots of establishing pangolagrass were seeded
with Stylo to compare yields and protein of this mixture with other legume grass
mixtures. Establishment was evident within two months. In September plants were
blooming vigorously and seeds were collected on December 2, 1963. About 10,000
pounds of dry matter were produced in the summer with crude protein contents of
9 to 17%. Even on December 2, when Stylo was almost mature, the crude protein
content was 9.2% compared to 4.0% for pangolagrass growing alone. Stylo seedlings,
from seeds produced in December 1963, were observed to be 1 to 2 inches tall in
late March 1964. The seedlings were very yellow when first germinated indicating
a lag between germination and inoculation. They eventually turn dark green.

CENTROSEMA PUBESCENS AND GLYCINE JAVANICA

These two summier-growing perennials have similar growth patterns but Glycine
is somewhat more frost tolerant. The difficulty with both is obtaining an early
maturing variety so that seed will mature prior to the first frost in the winter.

Centro has grown more rapidly and competes more easily in pangolagrass than
Glycine. Both produce large taproots which should permit their growth in well-
drained soils.